We aimed to identify a unique glycolipid which can exert potent stimulatory activity on invariant natural killer T (iNKT) cells and dendritic cells, while producing an adjuvant effect superior to that of α-GalCer. For this purpose, we performed step-wise screening assays on a focused library of more than 100 α-GalCer analogs. Assays had included quantification of the magnitude of stimulatory activity on human iNKT cells in vitro, binding affinity to the invariant T cell receptor of human iNKT cells, and binding to human and murine CD1d molecules. Through this rigorous and iterative screening process, we have identified a clinical "lead" glycolipid, 7DW8-5, which exhibits a superior adjuvant effect as compared to α-GalCer on HIV/malaria vaccines in mice. 7DW8-5 has demonstrated excellent safety, potent immunomodulating activity, and highly localized biodistribution in an extensive combination of mouse and non-human primate studies and will be tested in a Phase 1 clinical trial with healthy human volunteers in the near future.

Project 2 - Humanized Mice Model for Vaccine/Adjuvant Research

My laboratory has recently shown that a novel approach to introduce human genes encoding cytokines and HLA-A2, by AAV vector-mediated delivery, facilitates the reconstitution of human immune system (HIS), particularly A2-restricted human CD8+ T cells, in immune-deficient mice transplanted with human hematopoietic stem cells (HSCs). Briefly, NSG mice transduced with AAV9 encoding HLA-A2 and selected human cytokines resulted in higher levels of reconstitution of human CD45+ cells compared to NSG mice transduced with AAV9 encoding HLA-A2 alone or HLA-A2-transgenic NSG mice. Furthermore, the transduction of NSG mice with AAV-A2/hucytokines has led HIS mice to mount the highest level of antigen-specific A2-restricted human CD8+ T-cell response upon immunization with vaccines expressing human HIV/malaria antigens. Human CD8+ T-cell response induced in our HIS-CD8 mice can display A2-restricted cytotoxic activity against antigen both in vivo and in vitro. Most recently, we have been successful in generating HIS-CD4/B mice, in which both human CD4+ T cells and B cells are functional, thus being able to produce neutralizing human antibodies against a human pathogen.

Project 3 – Discovery of Carbohydrate-Specific T Cell, "Tcarb"

Infection with Group B Streptococcus (GBS), also known as 'Streptococcus agalactiae', can cause serious illness and sometimes death, especially in newborn infants, the elderly, and patients with compromised immune systems. The goal of this project is to determine the role of Tcarb cells in protection against streptococcal infection. Therefore, to accomplish this, we will first determine the physiological role of Tcarb, by investigating whether Tcarb can recognize and react with the GBS itself both in vivo and in vitro. We will then determine the role of Tcarb in promoting anti-glycan (GBSIII) antibodies in vivo, and whether Tcarb can mediate the protection against Streptococcal infection. We hope that our project will be able to change paradigm in T cell biology by shedding light on the important role played by Tcarb.

To provide answers to the mechanisms underlying the induction of protective anti-malarial CD8+ T cells, we have generated C57BL/6 transgenic (Tg) mice, in which a Kd molecule is expressed only on hepatocyte (Alb-Kd), macrophage (huCD68-Kd), or dendritic cell (DC) (CD11c-Kd), by using the albumin promoter, huCD68 promoter, or CD11c promoter, respectively. We have also generated MHC-I-Kd Tg mice, which express the Kd molecule under the MHC-I promoter, as a positive control. By immunizing these Kd Tg mice with various T cell-based malaria vaccines by various routes, we will be able to identify the type of antigen-presenting cells (APCs) that can induce malaria-specific CD8+ T cells that mediate protective anti-malaria immunity in vivo. Overall, we believe that the identification of the induction mechanisms of anti-malarial "protective" CD8+ T cells could ultimately lead to the vastly improved designs of potent T cell-based vaccines against human malaria. Click here to read more ...

Identification of novel synthetic analogues of alpha-GalCer, as an immuno-enhancing molecule for vaccines against HIV and malaria
Although many attempts have been made to develop HIV and malaria vaccines, they have been unsuccessful to date. The main reason for this failure is that the vaccines have not been immunologically strong, that is immunogenic enough to prevent the infection and/or to prolong anti-HIV/malaria immunity. Therefore, it is essential to develop a compound that can significantly enhance the immunogenicity of HIV/malaria vaccines. Our previous studies have demonstrated that a CD1d molecule-binding, natural killer T (NKT) cell ligand, alpha-galactosylceramide (alpha-GalCer), can enhance the immunogenicity of vaccines against HIV and malaria in a mouse model. Most recently, we have discovered that modification of alpha-GalCer can results in compounds with stronger biological activity (NKT cell stimulating activity) than alpha-GalCer. Therefore, our main goal is to determine whether some of the alpha-GalCer analogues could display a far superior immuno-enhancing activity, thereby greatly improving the efficacy of vaccines against HIV and malaria.

NAME: Moriya Tsuji, M.D., Ph.D.

ADDRESS:

HIV and Malaria Vaccine Program
Aaron Diamond AIDS Research Center
The Rockefeller University
455 First Avenue
New York, NY 10016